By the late 1980s and into the 90s, reports began to be received with increasing frequency in Europe and America of allergic reactions occurring among users of surgical and examination gloves made of latex and among spina bifida patients. The significant increase in the number of reports of latex allergy in the last decade has also been attributed to increased usage of latex gloves in healthcare in tandem with the rising cases of AIDS. Sensitisation to latex among healthcare workers is clearly work-related, the main cause being latex gloves, or specifically, the allergenic protein in latex gloves. Nevertheless, numerous cross-sensitivities between latex protein allergens and various food and pollen allergens are known. It is therefore not improbable that many latex-allergic patients may have been initially sensitised not only by proteins from latex products, but also by proteins from other sources.
There are hundreds of proteins found in natural rubber latex. Of these, only a small handful is allergenic (able to induce allergy). There has been much interest in identifying the proteins in Hevea latex responsible for latex allergy and considerable effort is expended on isolating and purifying the allergenic proteins from Hevea latex or latex products. Other than from the academic standpoint, elucidation of the major allergens in latex would enable antibodies to be developed against these proteins. Availability of the antibodies would facilitate the development of latex immunoassays, both for laboratory and commercial use. There are two main types of latex immunoassays    1. Immunoassays for Latex Allergy Diagnosis
These diagnostics are used to determine if someone is allergic or sensitized to latex. The assays can either be of the in vitro format (usually a serological test) or of the in vivo format (skin prick tests). These assays are used in research and in healthcare.    2. Immunoassays for the Quantitation of Latex Allergens in Manufactured Products
These quantitative assays determine the amount of allergenic proteins present in latex products. They are used for testing latex products such as latex gloves to determine the content of extractable latex allergens. Such immunoassays would be very valuable in latex product manufacture, particularly in the aspects of standardisation and quality control and quality assurance. The prospective customers for such immunoassays would be latex product manufacturers and regulatory agencies charged with the responsibility of ensuring product specification compliance.
Identification of the major latex allergens serves another useful function in healthcare. Purified latex allergens can be used in immunotherapy to de-sensitise latex allergic patients. When successfully undertaken, the patient no longer develops an allergic reaction to latex. This is especially important where the patient works in an environment (e.g. in healthcare) where latex products are ubiquitous.
Today, the International Union of Immunological Societies (IUIS) recognises ten latex allergens, Hev b 1 to Hev b 10. (There are other latex proteins under consideration by the IUIS.) Although there is effort being made to look for significant latex protein allergens, many researchers believe that most of the major latex protein allergens have been accounted for.
In 1995, Dr Donald Beezhold in his paper presented at Int Conf on Latex Protein Allergy: The Latest Position announced a new latex allergen that had partial protein homology to patatin, the major storage protein of potatoes. This 43 kDa protein is later assigned the WHO/IUIS name Hev b 7. When a recombinant version of Hev b 7 became available, it is found to be reactive with IgE from latex allergic patients. However, the proportion of patients that are sensitised to recombinant Hev b 7 is much lower than expected. Western blots that showed an active protein band around 43 kDa protein is much more commonly encountered than could be explained by IgE binding to Hev b 7. Hence, the recombinant Hev b 7 could not account for the very frequent occurrence of latex sensitivity to a protein of about 43 kDa. It is, therefore, possible that another unknown latex allergen of around 43 kDa existed. The search for this new and unknown protein has culminated in the present invention. This protein is allergenic in nature in that contact with allergenic latex protein (ALP) can induce an allergic reaction in persons sensitized to this protein.